If you have encountered this problem, please follow the guidelines here.
1. Please make sure that you have turned on the sound(You can check the volume option on the toolbar)
2. Please make sure that you have not turned off the sound of the current emulator in the multi-instance manager
3. You can try to switch the speaker in the system settings
4. Please check if the sound has been turned on in the Volume Mixer
If the previous solutions cannot solve your problem, you can try to uninstall NoxPlayer and download the latest version of NoxPlayer at: www.bignox.com